This is the menu that appears the first time you start Keypad mode.
It will show up in a vertical window on the right side of your screen.
Above this menu is the traditional Calc stack display. On a 24-line
screen you will be able to see the top three stack entries.

The ten digit keys, decimal point, and EEX key are used for
entering numbers in the obvious way. EEX begins entry of an
exponent in scientific notation. Just as with regular Calc, the
number is pushed onto the stack as soon as you press ENTER
or any other function key.

The +/- key corresponds to normal Calc’s n key. During
numeric entry it changes the sign of the number or of the exponent.
At other times it changes the sign of the number on the top of the
stack.

The INV and HYP keys modify other keys. As well as
having the effects described elsewhere in this manual, Keypad mode
defines several other “inverse” operations. These are described
below and in the following sections.

The ENTER key finishes the current numeric entry, or otherwise
duplicates the top entry on the stack.

The UNDO key undoes the most recent Calc operation.
INV UNDO is the “redo” command, and HYP UNDO is
“last arguments” (M-RET).

The <- key acts as a “backspace” during numeric entry.
At other times it removes the top stack entry. INV <-
clears the entire stack. HYP <- takes an integer from
the stack, then removes that many additional stack elements.

The EXEC key prompts you to enter any keystroke sequence
that would normally work in Calc mode. This can include a
numeric prefix if you wish. It is also possible simply to
switch into the Calc window and type commands in it; there is
nothing “magic” about this window when Keypad mode is active.

The other keys in this display perform their obvious calculator
functions. CLN2 rounds the top-of-stack by temporarily
reducing the precision by 2 digits. FLT converts an
integer or fraction on the top of the stack to floating-point.

The INV and HYP keys combined with several of these keys
give you access to some common functions even if the appropriate menu
is not displayed. Obviously you don’t need to learn these keys
unless you find yourself wasting time switching among the menus.

INV +/-

is the same as 1/x.

INV +

is the same as SQRT.

INV -

is the same as CONJ.

INV *

is the same as y^x.

INV /

is the same as INV y^x (the ‘x’th root of ‘y’).

HYP/INV 1

are the same as SIN / INV SIN.

HYP/INV 2

are the same as COS / INV COS.

HYP/INV 3

are the same as TAN / INV TAN.

INV/HYP 4

are the same as LN / HYP LN.

INV/HYP 5

are the same as EXP / HYP EXP.

INV 6

is the same as ABS.

INV 7

is the same as RND (calc-round).

INV 8

is the same as CLN2.

INV 9

is the same as FLT (calc-float).

INV 0

is the same as IMAG.

INV .

is the same as PREC.

INV ENTER

is the same as SWAP.

HYP ENTER

is the same as RLL3.

INV HYP ENTER

is the same as OVER.

HYP +/-

packs the top two stack entries as an error form.

HYP EEX

packs the top two stack entries as a modulo form.

INV EEX

creates an interval form; this removes an integer which is one
of 0 ‘[]’, 1 ‘[)’, 2 ‘(]’ or 3 ‘()’, followed
by the two limits of the interval.

The OFF key turns Calc off; typing C-x * k or C-x * *
again has the same effect. This is analogous to typing q or
hitting C-x * c again in the normal calculator. If Calc is
running standalone (the full-calc-keypad command appeared in the
command line that started Emacs), then OFF is replaced with
EXIT; clicking on this actually exits Emacs itself.